/**
 * Created with IntelliJ IDEA.
 * Description:
 * User:
 * Date: 2024-10-16
 * Time: 10:12
 */
public class BinarySearchTree {
    static class TreeNode{
        public int val;
        public TreeNode left;
        public TreeNode right;

        public TreeNode(int val){
            this.val = val;
        }
    }

    public TreeNode root;

    public void insert(int key){
        if(root == null) {
            root = new TreeNode(key);
            return;
        }
        TreeNode parent = null;
        TreeNode cur = root;
        TreeNode node = new TreeNode(key);

        while(cur != null) {
            if(cur.val < key){
                parent = cur;
                cur = cur.right;
            }else if(cur.val > key){
                parent = cur;
                cur = cur.left;
            }else{
                //不能插入两个相同的数据
                return;
            }
        }
        if(parent.val < key){
            parent.right = node;
        }else {
            parent.left = node;
        }
    }

    public TreeNode search(int key){
        TreeNode cur = root;
        while(cur != null){
            if(cur.val < key){
                cur = cur.right;
            }else if(cur.val > key){
                cur = cur.left;
            }else{
                return cur;
            }
        }
        return null;
    }

    public void remove(int key) {
        TreeNode cur = root;
        TreeNode parent = null;
        while(cur != null){
            if(cur.val < key){
                parent = cur;
                cur = cur.right;
            }else if(cur.val > key){
                parent = cur;
                cur = cur.left
            }else{
                removeNode(parent, cur);
                return;
            }
        }
    }

    private void removeNode(TreeNode parent, TreeNode cur) {
        if(cur.left == null){
            if(cur == root){
                root = cur.right;
            }else if(parent.left == cur){
                parent.left = cur.right;
            }else{
                parent.right = cur.right;
            }
        }else if(cur.right == null){
            if(cur == root){
                root = cur.left;
            }else if(cur == parent.left){
                parent.left = cur.left;
            }else{
                parent.right = cur.left;
            }
        }
    }
}
